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Replacement parts for GU2400XTP models | AppliancePartsPros.com
Your model number seems to be missing a couple digits.

Remove the kick plate.
Check that the float switch is activated (float is down).
Sometimes dirt etc. can hold the float in an up position so the unit thinks it is already over filled.

If OK
Check across the water valve for 120 volts when the unit is filling.

If there is no voltage, check for voltage across the fill valve and float switch combo. They are wired in series.
If you now have voltage, check across the float switch. If it has 120 across it then it is toast.

If there is no voltage across the combo odds are the control board is toast.

If there is voltage across the fill valve remove it from the machine and check/clean the screen filter on the input side of the valve. Do not permanently remove it, as it is there to keep crud out of the valve which could hold it open and cause a flood.
If the screen is clean the valve is toast.